It is known in beverage filling plants to fill carbonated beverages using the counter-pressure method, in which, prior to the actual filling with the fill product, the container to be filled is pre-pressurized with a pressure gas, and the carbonated fill product is then introduced into the container to be filled, which has been pre-pressurized in this manner and is hence under pressure. Through the application of the pre-pressure to the container, during the filling process there is no excessive release, or no release at all, of the CO2 that is present in the fill product, so that in this manner excessive foaming of the fill product can be prevented. The filling process can thereby be carried out quickly and precisely, since the end of the filling process, for example, when a predetermined fill height is reached, can be determined precisely using a fill level probe due to the substantial absence of fill product foam. Accordingly, a carbonated fill product can be filled quickly and precisely in this manner.
After the actual filling process, when all fill product is accommodated in the now filled container, the container is still at an overpressure. In particular, the head space of the container contains gas under pressure, which is substantially a mixture of the CO2 that is present in the carbonated fill product and the pre-pressurization gas. When the pre-pressurization gas is also CO2, the gas present in the head space is thus substantially CO2 under pressure.
Before the container can be conveyed to a further processing step, for example, a capper, it must be detached from the applicable filling element. Prior to this, the overpressure in the head space of the container must accordingly be relieved. For this purpose, the overpressure is relieved in a controlled manner by opening a relief valve. The opening of the relief valve establishes a fluid communication via a relief line between the head space of the container and the surrounding area, such that the overpressure present in the head space of the container can be relieved into the surrounding area when the relief valve is opened.
In the case of carbonated beverages, however, this leads to foaming of the fill product because the rapid relief of pressure in the head space causes spontaneous release of CO2 from the fill product to take place. This tendency to foam is particularly pronounced when beer is filled. The foam that arises in this way can then pass through the relief valve together with the expansion gas and enter the relief channel, through which it gradually travels. The mixture of expansion gas and fill product foam that is thereby present in the relief channel escapes from the end of the relief channel in an uncontrolled manner. At the end of the relief channel, the fill product foam usually drips onto the floor of the filling hall or into a gully.
The concentrations of the expansion gas, for example, CO2, that arise in the filling hall are in some cases undesirable.